The tedium/difficulty/expense of running cabling through walls and crawl spaces is something a lot of tech people seem to take for granted. Wireless is convenient(ish), particularly compared to the aforementioned, so most people are naturally going to gravitate towards it if that serves purpose.
Also, ethernet cabling available right at the front door is a security concern in itself. You need to be knowledgable of networking and have appropriate networking hardware to properly secure it against physical attacks.
This technology could just come built into these cameras which would be the responsible thing to do.
https://www.doorbird.com/downloads/datasheet_a1071_it.pd
It’s expensive, not weatherproof, and hard to order. Same for the one made by 2N. These both recycle old DSL technology I believe.
How difficult it is to install also depends on how your doorbell circuit is wired. Mine goes from a transformer in my basement to a switch on my door and from there to two chimes with a junction hidden somewhere. For these converters to work you need a straight run end to end.
I just installed an Amcrest doorbell which took me like 10 minutes. I'm using it with Scrypted to connect it to HomeKit. I didn't install it for security reasons. My old doorbell switch was broken and I figured as long as I needed to replace it, it would be nice to see what the heck my dog is constantly barking about.
If I wanted something for security reasons, I'd indeed use a PoE camera, but it wouldn't be a doorbell cam. There's very few PoE doorbell cameras in any case and they are quite a bit more expensive. And pulling an ethernet cable to the doorbell switch location would be non-trivial.